A conventional color image-forming apparatus has a plurality of photosensitive members juxtaposed in a prescribed direction. Specifically, the conventional color image-forming apparatus has four photosensitive drums arranged parallel to each other and juxtaposed horizontally. Electrostatic latent images can be formed on the photosensitive drums. This image-forming apparatus also includes four developing units, each of which has a developing roller confronting the upper region of a corresponding photosensitive drum, and an endless paper-conveying belt disposed beneath the four photosensitive drums for conveying sheets of paper in a horizontal direction.
In this image-forming apparatus, the developing roller in each developing unit supplies toner to the surface of a corresponding photosensitive drum in order to develop the electrostatic latent image formed on the photosensitive drum into a visible toner image. Next, the toner images formed on the photosensitive drums are sequentially transferred to and superimposed on a sheet of paper conveyed on the paper-conveying belt to form a color image on the paper.
The color image-forming apparatus also has a cleaning unit for removing residual toner deposited on the paper-conveying belt. The cleaning unit includes a scraping blade disposed so as to contact the paper-conveying belt, and a cleaning box. Residual toner scraped off the paper-conveying belt by the scraping blade is collected in the cleaning box.